Process of isolating fiber from bagasse



UNITED. STATES;-

PATENT OFF-ICE.

DOUGLAS E. SCOTT, OF BOSTON, MASSACHU'SETTS, ASSIGNOR TO ARTHUR D. LITTLE,

INCORPORATED, OF CAJDBRIDGE, MASSACHUSETTS, A CORPORATION OF MASSA PROCESS OF ISOLATING FIBER; FROM BAGASSE.

CHUSETTS.

1 399 891. Specification of Letters Patent.

No Drawing.

Toallwhomz't may concern:

Be it known that I DOUGLAS E. Soon, a citizen of the United States, residing at Boston, Roxbury district, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Processes of Isolating Fiber from Bagasse, of which the following is a spec1-' fication. v

This invention is a process of treating bagasse (the residue from the crushlng of sugar cane) for the purpose of preparing therefrom a clean fiber suitablefor papermaking or other purposes.

Efi'ortshave long been made, with varying degrees of success, to isolate from bagasse a fiber which should conform in all accompanies bagasse by reason of the conditions under which'sugar cane is harvested.

According to the present invention, the

bagasse in the form in which it is usually delivered by the sugar mill to the burners,

is preferably but not necessarily subjected to a sup lemental shredding, or shredding and crus ing, operation. The purpose of this treatment, for, which any of the standard shredding devices may be used, is primarily to shorten the time required for the subsequent operation; and the desirability of the supplemental shredding would of course depend somewhat upon the physical condition, including the state of subdivision of the bagasse itself for, as is well understood in this art, the physical condition of bagasse from different mills varies rather widely according to the intensity and number of the crushing, or shredding and crushing, operations to which it has been subjected.

Whether shreddedor not, the bagasse in the moist condition is charged into an apparatus designed and adapted "to disintegrate further and minutely the material into its structural elements and to do this in the Patented Dec. 13, 1921.

Application filed August 7, 1918. Serial No. 248,809.

presence of a relatively large proportion of water, which may well be twenty-five to 'fifty times the Weight of the bagasse. The ap aratus must be equipped with a suita le screening device adapted to wet screening and provided with screen of a mesh relatively very coarse as compared with the screens or wires heretofore used in paperby the relatively coarse mesh above mentioned.

The operation of separating thepith from the fiber is to be distinguished clearly from the common practice of washing the fiber in the beater. The latter operation is performed upon cooked fiber and has for its primary p lirpose the removal of soluble matters. ence the screen used is always of close mesh (usually about #70) in order to retain all vegetable structures and plant cells. In the present case, on the contrary, the treatment in the beater or equivalent devices precedes the cooking 0 eration, and'is so conducted as to accomplis a progressive breaking down or disintegration of the plant structure with coincident screening out and removal of the pith component. Consefl e tly th ize of the screen mesh must for the purpose of this process be of such order and dimensions as to permit passage of pith cells while preventing passage of fiber and fiber bundles. For this purpose a screen about 12 mesh is satisfactory.

The eating operation is more or less prolonged according to the physical state of the bagasse at the time of its introduction into the beater. In the case of bagasse which has been subjected to a supplemental shredding and crushing, treatment in the beater for about one hour will usually suffice to accomplish 'the desired results, comprising the latter as to bring it into the best condition for the subsequent cooking operation;

(2) \Vashing the pithy particles out through the washing cylinder, and thereby eliminating them so far as the paper-making operation is concerned. This phase of the treatment bears considerable resemblance to the washing of rag stock, except that in the latter case most of the material which is eliminated passes oil in solution.

(3) Eliminating a large amount of dirt and insoluble matter which could not be removed in course of any of the subsequent processes of paper-making. For example much of this dirt would fail to subside through the mass of stock in such way as to be caught by the sand-catcher of the beater; nor would it be caught by the screen of a paper machine. The rotary cylinder Washer covered with a relatively coarse screen as above described has proven highly effective both in the elimination of the pith and in the Washing of'the fiber.

The purified and washed fiber prepared as above is now ready for the cooking operation and for the subsequent manipulations by which it is converted into paper of the desired quality.

I claim 1. Process of isolating fiber from bagasse, which consists in subjecting the raw material in the presence of water to mechanical forces causing progressive disintegration of the material and detachment of the pith from the fiber and simultaneously removing the insoluble impurities and the pith by Screening while retaining the purified fiber.

2. Process according to claim 1 in which the raw material is preliminarily shredded.

In testimony whereof I afiix my signature.

DOUGLAS E. SCOTT. 

